The present invention relates to a rotary valve having a valve body rotatably mounted in a casing and adapted to be rotated to switch the flow of a fluid to operate an actuator of a robot, a manipulator or the like, and, more particularly, an arrangement including a driving device for directly driving the valve body.
An operating arrangement for a rotary valve operating for switching the flow of a working fluid should be simple, small, easy to control and highly responsive.
A rotary valve has been proposed wherein a pilot element for which a jet pipe or a nozzle flapper is used, and the valve body thereof is driven by an oil pressure amplifying element.
The above-noted proposed rotary valve has a complicated structure, since it is of a two-stage type, and allowance must be made for the capacity of a supply source of the working fluid for compensating an inevitable leakage in a jet pipe element. Additionally, since the jet pipe is a relatively small size, the jet pipe tends to be adversely affected by dirt, and this causes a problem in that a continuous strict control or monitoring of the quality of the working fluid is required.
In, for example, U.S. Pat. No. 3,858,484, a rotary valve is proposed wherein valve body is incorporated in a rotary actuator and that an entire operation from input to output is effected by a rotary motion.
A disadvantage of a rotary valve of this kind resides in the fact that it is not possible to achieve a high response time since an inertial load caused by a reduction gear, when rotation is imparted from a motor, is inputted through this reduction gear, and the control of the valve is reduced by the effect of the backlash of a gear train when a gear train is employed for the reduction gear.